The Genetics of Blue Eyes

Again I'm picking the brains of all of you genetics experts and breeders out there. A thread on blue eyed horses got me thinking, and it seems like its primarily paint horse genes that make blue eyes, at least according to some quick Googling (perhaps I'm wrong on that assumption, in which case please set me straight ). My guy has one blue eye and one brown, but no paint horse spots. Is that blue eye a clue that he has paint horse ancestors somewhere? I have no idea what his breeding is, so I'm not much help there. He does have lots of "chrome"; 4 high socks, a blaze, and a white lower lip, but no other white. As far as body color if he isn't a bay he's a very dark chestnut. Photobucket hates me, but there are pics in my "barn" here. So, is that blue eye and that white lower lip a hint toward paint genes, or is the "blue eye gene" completely independent of paint genes? I've seen other solid horses with blue eyes, and I've always kind of wondered where those "random" blues are coming from.

Thanks!

Two cream genes (double dilute) will give blue eyes: the horse would be cremello, perlino or smokey cream. Champagne will give greenish eyes.

But what you are talking about, yes, it's from pinto genes. All white markings are caused by pinto genes. The two that cause blue eyes are frame and splash. Your horse sounds like it's likely due to splash, as splash gives leg and face white. Frame likes to keep legs solid (but with other genes, frame positive horses certainly CAN have leg white).

Horses with no white markings but blue eyes are most likely frame.

Frame is the same gene as LWO. Two copies and the horse dies shortly after birth. One dose is just fine though.

I attemtped to check out your photos but they didn't want to enlarge for me :(

What CheyAut said, I was just about to point out it's pinto genetics, and most likely your horse does carry some form of pinto pattern. And like she said double dilutes have a different form of blue eye.

Both the horses that I have that have blue eyes are registered QH's that have little white on them. The sire doesn't have white eyes but throws colts that do sometimes.

Calling them "pinto genetics" can be confusing-- yes, the frame and splash genes that cause blue eyes are also known for causing white body markings at their higher expressions that make a horse eligible (depending on bloodlines of course) for full registry with the Paint and/or Pinto registries. But splash and frame can and do exist in primarily 'solid' breeds as well-- mostly at minimal expressions of face and leg white, sometimes a blue eye or 2 --- nothing that would be enough to call that horse as a pinto/paint.

Occasionally when these apparent 'solids' are bred, a fully pinto marked offspring will result (especially possible if both parents show clues of having minimally expressed splash and/or frame). This doesn't mean that the horse has Pinto or Paint ancestry--as in, ancestry that has full body spotting, or that is registered with either Pinto or Paint registries--It just means that the genes to make those potential markings existed in their ancestry and happened to combine with each other/just the right modifiers/etc. to have white patterning that is more highly expressed in that particular individual than it was in the parents and possibly any other known ancestor prior.

Exactly!

My neighbor bought an appaloosa stallion she bred to her three mares, one app and two QH, and two of the colts had one blue eye, neither had excessive white.

I would really love to see where someone has conclusively proven that white markings are caused by a form of pinto. The THEORY is that because we have only unlocked the genetic code to one form of sabino (sabino1) that there are other forms of sabino that cause the solid horses to have white markings. But it's a theory, and I don't understand why people are toting it as fact. It has not been studied enough to conclusively prove that as fact.